Colorectal cancer (CRC) incidence changes with time and by variations in diet and lifestyle, as evidenced historically by migrant studies and recently by extensive epidemiologic evidence. The worldwide heterogeneity in CRC incidence is strongly suggestive of etiological involvement of environmental exposures, particularly lifestyle and diet. It is established that physical inactivity, obesity and some dietary factors (red/processed meats, alcohol) are positively associated with CRC, while healthy lifestyle habits show inverse associations. Mechanistic evidence shows that lifestyle and dietary components that contribute to energy excess are linked with increased CRC via metabolic dysfunction, inflammation, oxidative stress, bacterial dysbiosis and breakdown of gut barrier integrity while the reverse is apparent for components associated with decreased risk. This chapter will review the available evidence on lifestyle and dietary factors in CRC etiology and their underlying mechanisms in CRC development. This short review will also touch upon available information on potential gene-environment interactions, molecular sub-types of CRC and anatomical sub-sites within the colorectum.

结直肠癌（CRC）的发病率随着时间以及饮食和生活方式的变化而变化，历史上的移民研究和最近的广泛流行病学证据都证明了这一点。全球结直肠癌发病率的异质性强烈表明环境暴露，特别是生活方式和饮食的病因参与。已证实，身体活动不足、肥胖和某些饮食因素（红肉/加工肉类、酒精）与 CRC 呈正相关，而健康的生活习惯则呈负相关。机制证据表明，导致能量过剩的生活方式和饮食成分通过代谢功能障碍、炎症、氧化应激、细菌失调和肠道屏障完整性破坏与结直肠癌增加有关，而与风险降低相关的成分则明显相反。本章将回顾 CRC 病因中生活方式和饮食因素的现有证据及其在 CRC 发展中的潜在机制。这篇简短的综述还将涉及有关潜在基因-环境相互作用、CRC 分子亚型和结直肠内解剖亚位点的现有信息。